\begin{tikzpicture}
    \tkzDefPoints{0/0/B, 3/0/C, 2/1.5/A}
    \tkzDefPoints{0/1.5/M, 3/1.5/N}
    \tkzDefPointOnLine[pos=0.6](A,B)  \tkzGetPoint{D}
    \tkzDefPointOnLine[pos=0.6](A,C)  \tkzGetPoint{E}

    \tkzDrawPolygon(A,B,C)
    \tkzDrawSegment(D,E)
    \tkzDrawSegment[dashed](M,N)
    \tkzLabelPoints[above](A)
    \tkzLabelPoints[left](B,D,M)
    \tkzLabelPoints[right](C,E,N)
\end{tikzpicture}

